Coil annealing convector plate



COIL ANNLINGCONVECTOR PLATE Filed Jan. e. 1967 Sheet FIG. 1.

Jall- 21, 1969 c. G. MCKEowN u COIL ANNEALING" CONVECTOR PLATE Sheet Filed Jan. 9, 196'? FIG-4.

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United States Patent 3,423,079 COIL ANNEALING CONVECTOR PLATE Charles George McKeown, Dudley, England, assignor to Wellman Incandescent Furnace Company Limited, Stafford, England, a British company Filed Jan. 9, 1967, Ser. No. 608,069

U.S. Cl. 263-47 4 Claims Int. Cl. F27d 5 00, 2.7 /00 ABSTRACT 0F THE DISCLOSURE A convector plate for use between two stacked coils of sheet metal during annealing of the latter, said plate cornprising two superimposed rib systems, each composed of a plurality of separate ribs arranged so that the ribs and the passages between the ribs together define an annulus, each rib being generally wedge-shaped in plan, and having straight edges which extend between the inner and outer peripheries of such annulus and are inclined in the same sense to the radii of the annulus, the ribs of each system having their outer ends substantially coinciding with the outer ends of the ribs of the other system, but being inclined to the radii of the annulus in a sense opposite to the sense in which the ribs of the other system are inclined to the radii of the annulus, and the rib systems being constructed so that air drawn inward along the convector plate toward the interior of the coils is separated into two sets of streams, one flowing through the passages between the ribs of one system and the other flowing through the passages between the ribs of the other system, the outer portion of each passage of one rib system, adjacent the periphery of the convector plate, being merged with a passage of the other rib system, and at least half of the remainder of each passage being separated from the passages of the other rib system to minimize interference between the flow through the remainder of each passage and the flow through the passages of the other rib system.

This invention refers to the so-called convectors which are spacer members used between coils of strip steel and like work pieces which are stacked one upon another for annealing in furnaces designed for this purpose.

It is customary to stack coils of strip steel or the like on edge, one coil upon the next and enclose all of the coils in a super-imposed cover, with a suitably designed furnace casing placed over the said cover, space being provided between the cover and furnace casing for the heating medium. A gas atmosphere is circulated continuously within the inner cover, passing downwards through the bore of the coils to a fan located in the base of the apparatus, and then upwards through the passage formed between the external wall of the coils of strip steel and the inner cover, thus completing one cycle. This circulation of the gas within the inner cover increases by convection both the rate of heating and of cooling and equalizes temperatures within the cover. The heating medium is positioned between the inner cover and outer furnace casing to provide the heat input for the annealing.

In order to speed the rise in temperature of the coils during the heating stage, and also to speed cooling of the coils when the annealing cycle is completed, it is customary to utilise the convectors as spacers between the adjacent ends of the coils and the convectors allow gas flow substantially radially between the outer periphery and the inner periphery of each coil.

One known form of convector for this purpose comprises an annular plate having a diameter approximately equal to that of the coils to be treated. For example it may be of seven foot diameter and some 1A" or more ICC Hence, the annular plate is sandwiched between each pair of ribs, comprising one rib on the upper face and one rib on the lower face, the upper rib being positioned precisely and geometrically above the lower rib. The ribs are usually parallel to secants of the plate, and hence the ygas flow inwardly of the convector is given a swirling pattern as it is drawn into the fan. It is well-known, however, that the pressure set up by the fan impellor is reduced if the air or gas entering the said impellor has an initial swirl in the direction of the impellor rotation, and hence the conventional arrangement referred to has the disadvantage of reducing the volume of air or gas handled by the fan due to the pressure set up by the fan being less than the system resistance. It is also found that at the temperatures concerned, for example of the order of 750 C., combined with the weight loading involved, the convectors are often subject to buckling.

The object of the present invention is to provide an improved convector for the purpose referred to.

In accordance with the present invention a convector for use in coil annealing is characterized by the provision of two superimposed rib systems which are oppositely related whereby gas flowing through the inter-rib spaces of the two systems will have imparted thereto a swirling pattern in opposite directions so that the resultant gas stream is rendered turbulent and substantially non-directional.

The two rib systems are secured together at the positions where they overlie one another. They may be directly secured to one another or to an intermediate plate. Each rib must overlie at least two ribs of the other systems and preferably it overlies three or four ribs. Each rib conveniently terminates on a common circle at the inner and outer ends thereof to form an annular convector. The outer ends of each rib may be curved to conform with the curvature of the plate.

Two embodiments of the invention are now more particularly described with reference to the accompanying drawings wherein:

FIGURE l is an end elevation;

FIGURE 2 is a plan view; and

FIGURE 3 is a section taken on the line 3 3 of FIG- URE 2.

FIGURES l to 3 all relate to the rst embodiment; and FIGURES 4, 5 and 6 are similar views of the second embodiment.

Referring first to FIGURES l to 3 of the drawings the convector comprises an annular plate 10 of relatively thin material having provided on both faces a pattern of ribs. The upper series of ribs are indicated by the reference 11 and the lower series of ribs by the reference 12. Each of the ribs is made of a thicker material than the plate 10 and each rib is of an irregular quadrangular shape. The upper set of ribs 11 are all substantially tangential to the inner periphery of the annular disc 10. As best seen in FIGURE 2 the ribs increase in width from the end located nearest the inner periphery of the annular disc to a maximum width at their outer extremities, so that the spaces 13 between adjacent ribs taper from a maximum width at the outer periphery thereof, but the tapering effect is only small.

The pattern of ribs 12 is the mirror image of the pattern 11 and each upper rib 11 has its outer end or tip superimposed upon the outer end or tip of one of the lower pattern of ribs.

Hence as seen in FIGURE 2 each upper rib extends across four ribs of the lower set or pattern. This is also illustrated in FIGURE 3 where the line 3-3 is taken through the length of One of the upper ribs 11 and one of the lower ribs 12.

Each of the ribs is secured to the annulus 10 by welding or by rivets or any other convenient means.

Referring now to FIGURES 4 to 6, the construction shown therein is substantially identical to that in FIG- URES l to 3 except that the annulus 10 is omitted and consequently the ribs of the lower pattern or set are secured to those of the upper pattern or set directly.

The arrangement shown in both embodiments produces a rigid and robust structure.

In use the convector according to FIGURES 1 to 3 or according to FIGURES 4 to 6 is located between a pair of coils of sheet metal with the axis of the coils co-axial with that of the convector, and the convector provides a gas ow path particularly between the adjacent coils, and hence allows llow from out of the spaces 13 into the coil interstices on either side of the convector. This gives etlicient and rapid heating or cooling of the coil faces adjacent the convector.

Moreover, the invention also provides the surprising result of greatly increased heat up and cool down rates, and it is believed that this is due to the turbulence in the bores of the coils as a result of the patterns of ribs being oppositely related since gas flowing into the spaces 13 in the upper set, as viewed in FIGURE 2 or FIGURE 5 tends to have a clockwise swirling motion imparted thereto, whereas the gas flowing through the spaces 13 in the lower pattern or set as viewed in the same figures tends to have an anti-clockwise swirling motion imparted thereto. This encourages mixing of the streams of gas and hence produces a turbulent and non-directional gas stream in the bores of the coils owing towards the fan or impeller.

The embodiment shown in FIGURES 4 to 6y is preferred because problems of buckling are reduced or eliminated.

I claim:

1. A convector plate for use between two stacked coils of sheet metal during annealing of the latter, said plate comprising two superimposed rib systems, each composed of a plurality of separate ribs arranged so that the ribs and the passages between the ribs together dene an annulus, each rib ibeing generally wedge-shaped in plan, and having straight edges which extend between the inner and outer peripheries of such annulus and are inclined in the same sense to the radii of the annulus, characterized in that the ribs of each system have their outer ends substantially coinciding with the outer ends of the ribs of the other system, but are inclined to the radii of the annulus in a sense opposite to the sense in which the ribs of the other system are inclined to the radii of the annulus, and in that the rib systems are constructed so that air drawn inward along the convector plate toward the interior of the coils is separated into two sets of streams, one owing through the passages between the ribs of one system and the other flowing through the passages between the ribs of the other system, the outer portion of each passage of one rib system, adjacent the periphery of the convector plate, being merged with a passage of the other rib system, and most of the remainder of each passage being separated from the passages of the other rib system to minimize interference between the fiow through the remainder of each passage and the flow through the passages of the other rib system.

2. A convector plate according to claim 1 wherein the two rib systems are secured to the opposite sides of an annular plate.

3. A convector plate according to claim 2 wherein the outer ends of the ribs extend beyond the periphery of the annular plate.

4. A convector plate according to claim 1 wherein the two rib systems are directly secured to one another, and each rib of one system overlies not more than four ribs of the other system.

References Cited UNITED STATES PATENTS 2,671,656 3/1954 Winder 263-47 2,678,815 5/1954 Radlinski 263-47 3,145,982 8/1964 Ludwig 263-47 JOHN I. CAMBY, Primary Examiner.

Notice of Adverse Decisions in Interferences In Interference No. 97 ,256 involving Patent No. 3,423,079, C. G. McKeown, COIL ANNEALING CONVECTOR PLATE, final judgment adverse to the patente@ was rendered May 18, 1973, as to claims 1 and 4.

[Oycz'al Gazette 00170561' 23,1973] 

